“Lipid mediators are produced from the oxidation of polyunsaturated fatty acids through enzymatic and free radical-mediated reactions. When subject to oxygenation via cyclooxygenases, lipoxygenases, and cytochrome P450 monooxygenases, polyunsaturated fatty acids give rise to an array of metabolites including eicosanoids, docosanoids, and octadecanoids. These potent bioactive lipids are involved in many biochemical and signaling pathways, with inflammation being of particular importance.” (Massey KA and Nicolaou A, Free Radic. Biol. Med. 2012).
When considering membrane lipids, especially phospholipids, one always thinks of static molecules, which serve only as an instrument for the cell compartmentalization. At most, one considers quantitative characteristics such as fatty acid unsaturations, which are indexes of greater or lesser fluidity of the membrane network.
Rarely, the qualitative importance of these fatty acids is taken into account, especially of those fatty acids that are targeted by the Phospholipase A. They turn out to be even more important when they are released rather than when they are present in the membrane, through the transformation into potent bioactive molecules involved in homeostatic and pathophysiological cellular events.
In particular, DGLA (Dihomo-Gamma-Linolenic Acid), EPA (Eicosapentaenoic Acid), AA (Arachidonic Acid) and DHA (Docosahexaenoic Acid) are the fatty acids from which the most important and best known metabolites are originated (i.e.: Eicosanoids, Resolvins, Protectins, Neuroprostanes, etc.). The intracellular effects that are generated are finely balanced by the spatio-temporal quantities of these metabolites and by their original pathways.
Fatty acids as intracellular mediators: once again, everything originates from the membrane network.